1. Field of the Invention
The present invention relates to an air conditioner, and more particularly, to an air conditioner in which some of a plurality of outdoor heat exchangers may implement a defrosting operation and others may implement a heating operation.
2. Discussion of the Related Art
Generally, an air conditioner is an apparatus to cool or heat a room by using a refrigeration cycle including a compressor, an outdoor heat exchanger, an expansion unit, and an indoor heat exchanger. Specifically, the air conditioner may include a cooling unit to cool a room, and a heating unit to heat a room. In addition, a combined cooling/heating air conditioner to cool or heat a room may be realized.
The combined cooling/heating air conditioner may include a 4-way valve to change a flow of compressed refrigerant from the compressor depending upon whether a cooling operation or a heating operation is selected. During the cooling operation, the refrigerant compressed in the compressor is directed to the outdoor heat exchanger by way of the 4-way valve with the outdoor heat exchanger serving as a condenser. The condensed refrigerant after having passed through the outdoor heat exchanger expands while passing through the expansion unit and thereafter is introduced into the indoor heat exchanger. In this case, the indoor heat exchanger serves as an evaporator, and the refrigerant evaporated in the indoor heat exchanger is returned into the compressor by way of the 4-way valve.
On the other hand, during a heating operation, the refrigerant compressed in the compressor is directed to the indoor heat exchanger by way of the 4-way valve with the indoor heat exchanger serving as a condenser. The condensed refrigerant after having passed through the indoor heat exchanger is introduced into the outdoor heat exchanger after being expanded in the expansion unit. In this case, the outdoor heat exchanger serves as an evaporator, and the refrigerant evaporated in the outdoor heat exchanger is returned into the compressor by way of the 4-way valve.
During the above described operation of the air conditioner, condensed water may form on a surface of the heat exchanger serving as an evaporator. Specifically, the cooling operation may cause condensed water to form on a surface of the indoor heat exchanger, whereas during the heating operation may cause condensed water to form on a surface of the outdoor heat exchanger. If the condensed water formed on the surface of the outdoor heat exchanger during the heating operation freezes, smooth flow of outdoor air may be prevented, and a heat exchange efficiency between the outdoor air and the refrigerant may deteriorate, resulting in poor heating performance.
Accordingly, to remove the condensed water generated during the heating operation, one might consider temporarily stopping the heating operation and driving the refrigeration cycle in reverse (i.e. to initiate a cooling operation), so that high temperature and high pressure refrigerant is directed to pass through the outdoor heat exchanger, causing any frost formed on the surface of the outdoor heat exchanger to melt due to the heat of the refrigerant. However, implementing a defrosting operation as described above via reversal of the refrigeration cycle has the problem of stopping the heating of a room.